rigged results in dyno tests in magazines

grumpyvette · Jun 17, 2009

one of my pet peeves is rigged results from testing, in those magazine dyno results, we all read frequently,as most of the experienced guys know the engine is a SYSTEM of parts that must match in the rpm range and air flow/ horse power levels they need to run at to get valid results
anyone can take a nearly stock 350 Chevy engine designed to run at 3500rpm or lower rpms most of the time and show a marked advantage in the power curve,on a dyno for the use of a well designed dual plane intake and matched 650 cfm carb,over the stock o.e.m intake and carb, or a well designed single plane intake, with a 850 cfm race carb and matched cam, and heads, on that same engine. Especially if the dyno run in that article only goes to about 4500rpm-5500rpm, yet there's not a thing wrong with the single plane intake, or a race cam or the O.E.M. parts if they are used under conditions they were designed to be use under,
the opposite result would be shown on a similar 350 engine equipped with an aggressive cam, high compression pistons, open headers and cylinder heads designed to run 7500rpm , if your testing intake manifolds, especially if the dyno testing started at 3500rpm and pulled to 7800rpm.
IVE found over the years that magazine dyno test results depend a great deal on the company that's paying for the testing to be done and the components they sell, seldom does the company's products come out looking badly,
automotive magazines have always been seen by the parts manufacturers as a less expensive way to promote extended advertising of the parts they want sold, they arrange for a minimal tech related blurb, and slant it's results, as far as they can stretch reality to make their product look totally indispensable
EXAMPLE
Ive had very good results with BOTH CLOYES chain drives and JACKSON cam drives, and ID doubt theres a two hp difference between them on an honest dyno test, in most engine combos.
yet Ive seen dyno test results in magazines, that say theres a 5% reduction in power for a gear drive (thats 25hp on a 500hp engine) that result is ludicrous, but its also easy to "PROVE" a chain drive OR a cam drive is superior with a skilled dyno operator doing the testing

I just got thru reading a DYNO test on oval versus rectangle port heads on a bbc engine in one of the magazines, now the results they got while valid, for the tested engine combo, were intentionally rigged in my opinion, they were not a fair comparison, and any engine builder with experience would have picked up on the fact that the DYNO test was set up so that only one result was likely.
honestly some of the tech, used in magazine dyno testing, is absurd, it would rank up with some guy claiming ice made by the refrigerator he sells, never melts, and for a test he would leave a bag outside on the ground for a week in Antarctica in the middle of winter , to prove it!

in the article they first matched results on a 454 using rectangle then oval port heads, the results was 407hp (R) versus 419hp(O) N/A
then 558hp(R) versus 563hp(O) SUPERCHARGED
now that's fine UNTIL YOU LOOK AT THE OTHER COMPONENTS USED
in the first test a cam was used with only 220/220 duration and .500/.500 lift,and the dyno was only run up to 5700rpm. now any engine builder knows that the advantage of the rectangle port heads will not show up until a cam is used that's been designed for rpm ranges of about 5000-6500rpm plus and lifts in the .550 plus ranges are used, and in most cases theres factors like compression ratio,displacement, exhaust scavenging,, cylinder heads being used, duration and lift of the cam, the cams LSA, and a good deal more factors that will have a very noticeable effect on your dyno power curve results.
MOST ENGINE BUILDERS WILL TELL YOU THAT CORRECTLY SET UP OVAL PORT HEADS ARE THE BEST CHOICE ON THE AVERAGE mild STREET,ENGINE COMBO, AND THEY ARE CORRECT! but in this case a look at the dyno torque curve shows very clearly the CAM selected for the testing, started causing the engine to run short on air at about 4300rpm, to 4500rpm, this meant the rectangle port heads had no chance at ever reaching the rpm range, that the larger port heads were designed to run in, efficiently.. in the second test, in that article, a supercharger was used on both cylinder heads, but it was a HOLLEY 174 power charger DESIGNED for efficient low rpm street use ,that's a supercharger that's not designed to feed a 454 displacement at anything close too 6000rpm, and again the same low rpm efficient cam ,design was used, that severely limited power potential at over about 4300rpm-4500rpm.
if you only open the valves enough to flow at the smaller tested ports limitations on both heads tested your obviously restricting the larger port heads potential, if your only allowing the engine to operate in the smaller ports head flow efficient power band the larger port head can never be expected to show any advantage, in fact its lower port speeds in the tested range are obviously going to be less efficient just as the smaller port would be if pushed well past its effective flow limitations in the higher rpm ranges
if your going to compare the results fairly to take ADVANTAGE of the STRONG POINTS OF BOTH CYLINDER HEADS, a longer CAM duration, used in a high compression engine combo and a LARGER SUPERCHARGER would need to be used, to show the marked superiority of the larger port heads with both sets of heads being tested along with the milder combo so you could see why the larger ports have advantages and dis-advantages , depending on the other components they are matched too, I would be VERY SURPRISED if the results still favored the oval port heads if both cylinder heads were tested with a cam like the CROWER #01488,
http://www.crower.com/misc/cam_spec/cam_finder.php

with a N/A dynamic compression ratio of about 8:1, which would obviously require a boost in the static compression ratio,

or if the HOLLEY, 871 supercharger driven at 1:1 engine speed ratio and spun up to 6000rpm was used on both engines with a lower compression matching the supercharges boost curve

http://www.holley.com/types/Big%20Block ... Series.asp

rectangle port heads generally work best on 500 or larger displacement engines
with at least 10:1 compression and cams with at least 245 duration at .050 lift and valve lifts over .600 to take advantage of the potential port flow rates

Big_G · Jun 17, 2009

Good points. Brings to mind a flawed comparison on a sbc that David Vizard did a few years ago. It was an intake manifold comparison...Performer RPM dual-plane v. a Vic. Jr. single plane. I believe it has a modest cam also, and only 180cc heads. The dyno pull clearly showed an advantage to the dual-plane, but the engine was falling off on power with both manifolds at about 5,500. That says the heads/cam were giving a huge advantage to the dual-plane. The Vic. Jr never had a chance. I am surprised David V. let that slide. You begin to wonder the credibility of the author of those type of tests and the back-door dealings with the manufacturers.

grumpyvette · Oct 7, 2010

I recently read a magazine test in some trucking magazine while I waited in a doctors office waiting room,
where they swapped mufflers , on a large 4x4 truck , that already had headers installed,and the resulting change showed something like a 25 horsepower gain in power , (the change in muffler brands got all the credit)
it was only when you carefully read thru the article that you found that the old mufflers and exhaust were a 2.5" size with a balance tube design and the new exhaust system and dual exhaust was a 3" system with an (X) pipe.
Id bet a huge percentage of those gains were the result of the far less restrictive to flow 3" exhaust and (X) pipe, well before the mufflers were even a factor.
I don,t know how most guys learned, but in most of my freinds and my own case, we had to learn thru a long series of wasted cash, bogus parts, and getting screwed by various machine shops as we eventually learned that a great deal of what you read in the hot rod related magazine articles is either wildly optimistic, or assumes, you know that most of the claimed gains are only available if other matching required mods or machine work they conveniently forget to mention are also done, or that in a certain application those gains that make you want to rush out and buy the parts advertised, in those magazine articles, were artificially increased by stacking the deck, in that parts were deliberately matched in such a way as to make the advertised part the cure for a huge intentional,pre -selected mis-match in components .
as you gain experience you pick up on the little tricks they play, but a new guy to the hobby would never know that the magazine articles in many cases are deliberately slanted to stack the deck in such a manor as to give the manufacturer of the components they are pushing a huge advantage in the dyno results so you can,t wait to rush out and buy the (WONDER COMPONENT of the MONTH)

Id also point out that OWNING , or running ,a speed shop or machine shop , or working at one may not mean you know squat about making an engine run to its full potential,
but it will generally mean your fully submerged in the process of learning, what works and sells or you'll eventually be out of business.
Ive dealt with several skilled machinists and welders, and dozens of
(speed shop employees that were skilled in their particular area of expertize that were all but clueless , in many areas of engine building ),
simply because they do not need to know or in some cases even care to learn about those areas.
you always need to do research on what your trying to do and recognize the fact that theres a ton of mis-information being tossed around on the internet and from other sources based on selling merchandise at a profit,or based on what might have worked on a totally dis-similar application, rather than what really works best, in some car similar to YOUR application.
guys who have a winning combo rarely want to give their competition all the FACTS about WHY their car is faster or why it continues to run well while the competitors constantly break down.
and performance magazines get paid big bucks to promote the sale of certain components , by manufacturers ,regardless of the real documented results of careful comparative testing.
one good example I know about is that many times you'll read about some engine combo and they may list a certain intake manifold or cylinder heads or a certain cam being used, they also fail to mention the fact that there may have had many additional hours of welding and port work done to those heads or that intake design, or ordered the cam on a much tighter 104 LSA vs the stock 112 LSA, and use it with a different rocker ratio,or conveniently omit the fact that you need some additional component work to get those parts to run efficiently like aftermarket valve train components like vascojet,valve springs,titanium retainers,or some expensive sodium filled exhaust valves, or they forget to mention the 2" titanium exhaust valve and 5 angle valve job on the big block turbo heads

grumpyvette · Feb 3, 2011

its possible, in most cases to to get realistic results that approximate the software dynos wild guess at FLYWHEEL HP
but its NOT reasonable, to always expect an exact match because the software rarely bases it results on exact measurable data.
theres a rough guide you can use if you find obviously questionable results from software dynos
,youll generally find your street/strip American V8 running pump octane fuel,based engine will produce about 1-1.25 ft lbs of torque PER CUBIC INCH of displacement,at about 80% of max rpm, horsepower will depend on several factors but lets look at the formula for hp
torque x rpm /5252=hp
so if you made lets say
1.1 ft lbs of torque at a semi reasonable max piston speed for a street car combo of 4000 feet per minute
we find the 402 spinning at 6400rpm and the 496 spinning at 5650rpm
plug in the formula and we get
402 x 6400rpm x 1.1=538hp/442 ft lbs
496 x 5650rpm x 1.1-587hp/545 ft lbs

now obviously you can, boost both results but those are about the median results youll see from those engine displacements using basically common aftermarket, or re-worked stock components on an engine thats still built for street use

DorianL · Feb 4, 2011

I am trying to find an articl back for you guys. I want to scan the page and post it once I find it.

The mag dynoed an 800HP supercharged plant. But the static compression was significantly over 10:1. I wonder how they did that?

grumpyvette · Sep 28, 2012

http://www.nicoclub.com/archives/the-dy ... ement.html

The Dyno Game – Why dyno charts of aftermarket parts may not be a valid measurement

Automotive speed enthusiasts are always looking for the latest gadget to throw at their vehicle in pursuit of increased horsepower. As auto manufacturers strive to somewhat meet these consumers needs by releasing models with increased output (Less restrictive intake and exhaust systems, more aggressive ECU tunes and larger/more powerful engines are examples), the aftermarket parts manufacturers strive to supply owners with alternative designs to meet this growing demand for more power. Aftermarket products can vary widely from a simple intake to complex forced induction kits and it is up to the consumer to determine what they are looking for and how much they are willing to pay in order to meet their own goals.

Upon releasing a new product, aftermarket manufacturers usually post up dyno (Chassis Dynamometer) graphs to show how much power their “test mule” was able to put out while utilizing this new product.Hence, an expectation level is set for that product to the target consumer. For those not “in the know”, a dyno is a machine used to measure torque and rotational speed (RPM) from which power produced by an engine may be calculated. During this test,the vehicle is strapped down to the dyno and air is blown over the engine via a fan to assist with cooling while imitating airflow since the vehicle is stationary. The vehicle then performs a “run” which is measured and graphed. The question is, are these stated graphs to be trusted? The answer is “no”.

Wait, did I just state that the whole aftermarket community is falsifying information in order to obtain a sale?Of course not. I am simply saying that there is more than meets the eye in regards to the gains that are claimed as attributed to these individual parts and that the peak levels shown on these dyno graphs can be misleading.In some cases, they can be absolutely false as well. Let’s look at some of the ways that a dyno graph can be misleading or that peak output may be manipulated.

Hot vs. Cold

Engines produce the most peak horsepower when they are cold. As the engine comes up to normal operating temperatures, peak output will settle to a lower level. Extensively running the motor will lead to “heat soak” which further lowers an engines output. It is very easy for manufacturers to post peak cold-engine dyno results in comparison to baseline results that were performed on a hot or heat soaked motor. An example of this is the 2002 Nissan Performance Magazine test of the Nismo intake on a 3.5L Altima. Should you read the article, you will note they show 12.9whp increase and 25.6whp peak during their dyno test. If you read further, you will see that their peak numbers were during a “cold” run. The dyno charts on that article tell the real story as base-line (run 2) showed 216.91whp, run 4 (cold run) with the intake shows 229whp and run 5 (intake with hot engine)shows 218.53whp. So in effect, a hot-run base-line was 216.91 and a hot-run with the intake was 218.53whpwhich results in the aftermarket intake providing +1.62whp. That’s a far cry from 12.9whp as initially claimed.

Temperature
The warmer the temperature the less power will be made. Performing a base-line test during a hot afternoon while performing a post-install test in the cooler evening air will give better results to the later dynotest.

Being crooked
While it is highly doubtful that major manufacturers would partake in such, there are ways to change the dyno or the environment itself to give better numbers if desired. Crooked dyno operators can adjust the weight of the drum, adjust the straps holding the vehicle down, program the dyno to a different air temperature level or SAE correction levels, adjust the dyno elevation and reprogram the weight of the drum itself. Additionally, having the A/C running for the base run, not opening the hood and using a fan for airflow or performing the tests in different gears can also give the illusion that the “part” is better than it is .Finally, a base-run from a completely separate vehicle could easily be utilized.

Owners of the parts themselves can easily mistake power gains based upon perception. This is usually referred to as a “butt-dyno” in the sense that the owner feels that the vehicle is more powerful without any proof. In the case of a new intake or exhaust system, the butt-dyno again is quite misleading as other senses can lead to this perception. Think about it for a minute. You know you have a new “performance” part installed and the engine is much louder during a WOT run. Thus, you perceive more power when that power may not be there at all or is far more minimal than you think. Nothing wrong with that, but perception is not necessarily reality. As with the test mentioned above, do you really think someone can really feel 1.62whp once the car warms up?

With the above said, there is definitely a place for these simple bolt-ons. Since an engine works as an air pump, increasing the amount of air into the motor will somewhat help just as increasing the amount of air that can be dispelled via an exhaust system. Installing both an intake and exhaust system together can actually increase the total amount of power to a higher level than the amount each individual component can offer by themselves. Just be aware of claims vs. reality and do not set your expectation levels too high.

why is it that darn near everyone just reads a few magazine articles and assumes that when they show remarkable gains from a cam swap that they don,t mentally step back and ask what to me is an obvious question, "WHAT DID YOU DO THAT YOU FAILED TO MENTION?" like new valve springs ,new rockers, larger injectors porting etc. look the fact is that most stock valve trains are not designed to run at over 6000rpm, and most cars have injectors sized for the original power level, and most cars have automatic transmissions and rear gear ratios , and compression ratios more designed to lower emissions and increase mileage than to maximize peak power, so swapping a new more aggressive cam MANDATES other changes, like long tube low restriction headers and a low restriction exhaust behind the headers, to allow it to function to its full potential, and additions like an additional trans fluid cooler to math the higher heat produced by a higher stall speed torque converter and a different rear gear ratio, and better valve springs, higher cost roller rockers and porting the heads and intake is conveniently ignored,and that the original stock parts won,t work well with the new performance cam, without the parts they forgot to mention when that miracle cam jumped the peak power 80 plus hp is simply ignored, as posting that info might reduce sales of the cam the articles pushing for sale are not compatible with a noticeably longer duration cam

http://garage.grumpysperformance.co...dyno-test-results-on-an-ls3.10416/#post-43247

http://garage.grumpysperformance.co...ine-info-from-diferent-sites.5611/#post-17135

http://garage.grumpysperformance.com/index.php?threads/chevy-ls1-related-info.3918/#post-10424

http://garage.grumpysperformance.com/index.php?threads/418-cid-ls3-build.2033/#post-5418

YES ONE OF THE THINGS ALMOST ALL MAGAZINE ENGINE BUILDS, SKIP!
they purposely
SKIP OVER IS THE LONG MACHINE SHOP AND PART ORDER TIME FRAMES,
SHOP LABOR COSTS,
AND MOST CASH CONSUMING DETAILS, on the ENGINE BUILDS
little things like having to spend 45 hours porting the heads and intake,or clearance milling the block, or welding on the oil pan,to get them functioning correctly, or having to junk the original valves and valve springs and retainers to get the proper geometry, just get ignored
and concentrate on promoting this month favored part vendors product
most engine builds are at best thinly disguised advertisements for some vendor, or LIST OF VENDORS components
notice the list of manufacturers commonly listed in the article
youll rarely if ever see any detailed description of the valve train components
what the exact valve train clearances were the type of valves used the multi angle valve jobs
the back cuts on valves
what the part number was on the valves, or keepers, retainer, valve springs, shims cups clearances.

http://garage.grumpysperformance.co...s-in-dyno-tests-in-magazines.1817/#post-26481

http://garage.grumpysperformance.co...lve-seat-angles-and-air-flow.8460/#post-31961

http://garage.grumpysperformance.co...olishing-combustion-chambers.2630/#post-21649

http://garage.grumpysperformance.com/index.php?threads/multi-angle-valve-job-related.3143/#post-8387

http://garage.grumpysperformance.com/index.php?threads/valve-springs.9613/#post-50556

http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46658

http://garage.grumpysperformance.com/index.php?threads/valve-springs.9613/#post-35611

http://garage.grumpysperformance.co...ting-up-the-valve-train.181/page-2#post-19783

http://garage.grumpysperformance.com/index.php?threads/how-to-lap-valve-seats.1159/#post-2362

http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46662

http://garage.grumpysperformance.com/index.php?threads/removing-valve-seals.4283/#post-44288

http://garage.grumpysperformance.co...per-valve-spring-seats-shims.1005/#post-15534

http://garage.grumpysperformance.co...oper-valve-spring-seats-shims.1005/#post-1818

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/#post-4041

http://garage.grumpysperformance.co...-octane-for-compression-ratio.2718/#post-7057

grumpyvette · Sep 28, 2012

WA 2 FST....POSTED THIS BIT OF INFO

"THIS is really simple in my mind, but most people do not get it. You do NOT shift at peak engine HP. This is the biggest crock, and yet that's what you'll hear from all the dyno queens. You are not really _using_ that peak HP # if you're shifting there. Also, it is NOT TQ that wins races, but average HP under the curve. I'm not even going to debate this, but before someone starts in on me, yes I know that HP is just a function of TQ. Having "good average HP" means you have a nice TQ curve. But what your car does at 1500-2500rpm is meaningless in a racing environment.

But if you're looking at a graph and you want to know where to shift, you need to know the gear ratios of your transmission and how they correspond as a percentage of one another on the subsequent upshift. Let's assume that 2nd gear is roughly 65% of 1st gear as far as the ratio goes. So, when you upshift, you will drop to 65% of whatever rpm you shifted at. Assume you shift at 6600rpm, then your revs on the upshift will drop to ~4300. 3rd might be 75% of 2nd, so on the 2-3 upshift, you would only drop to ~4950.

Whatever the case is, you need to find what the best average HP yield is given a specific rpm range and that will determine where you need to shift. Quite often on these cars peak HP is ~6000-6200rpm. So just take all the data of HP in 100rpm increments, and figure out where the best average is. Typically, this will result in you shifting 1-2 farther out than the 2-3, 3-4 upshifts because, again, the rpms fall more on the 1-2 than the others.

For a typical centrifugal supercharger application, peak power will be redline if you're subject to the stock rev-limiter (6600). This is inefficient, but this doesn't mean the car will be slow. It will mean the car will run slow(er) ET/MPH than what its peak HP # suggests, though. There is no getting around this.

If you don't want to fool with plotting the data, then a good rule of thumb is shifting 200-300rpm past the peak HP. This will give you a much better "average HP available" than shifting AT peak HP.

But really the best way to do it is to plot the data. For instance, let's say you see a chart where the peak HP occurs and then almost immediately the power starts to fall off really fast. Obviously here you would want to upshift much quicker than if you had a very flat HP curve as it approaches and passes the peak rpm at which HP is achieved. The stock LS6 may make peak HP at 6000, but it also only drops 5-10rwhp at 6600rpm. This is not enough of a drop to shift anywhere _before_ 6600 b/c on the upshift, you will be much lower than 5-10rwhp from peak. Making sense?

As far as #2 goes... this is where low-end TQ does come into play...getting the car moving from a low-rpm roll or off idle from a standstill. Ideally you'd want a car with as flat of a TQ curve as possible. HP is a function of TQ at a certain rpm. Obviously at low rpms, you need more TQ b/c you don't have rpms yet to make power. A "soft" low-end TQ curve will require lots of rear gearing/trans gearing to get the engine up into its happy zone. Once done, if you manipulate the upshifts properly (meaning NO short-shifts) you're good to go. But a broad TQ curve will allow the user to accelerate well in just about any gear, which makes for a more pleasureable driving experience, particularly on the street.

As far as dyno graph tips go... I would be more impressed with a HP curve that has some meat underneath it. One that goes straight up, diagonally, as a function of rpm isn't horrible, but its not making the most "average" HP, compared to another that makes more power earlier on (again this is where TQ is most important) and then flattens out... even if its peak is a bit less than the former example."

grumpyvette · Sep 28, 2012

viewtopic.php?f=71&t=555

viewtopic.php?f=71&t=741

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you may find these links useful

Grumpy · Oct 13, 2016

http://www.hotrod.com/articles/ccrp-0411-block-test-rodent-wrestle-fest-tech/

heres a good example of a purposely RIGGED dyno result, they purposely used large rectangle port heads on a 454 BBC and if your familiar with building the BBC engines you know the engines of 500 cubic inch displacement and less tend to produce both better peak power and average torque with the better OVAL PORT HEADS, the rectangle port heads start to become much more effective once you hit or exceed 540 cubic inches

http://garage.grumpysperformance.co...ill-subscribe-to-various-car-magazines.14489/

http://garage.grumpysperformance.com/index.php?threads/big-block-chevy-info.710/#post-60299

http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/

rigged results in dyno tests in magazines

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